Conventional box-like structures made of metal or plastic panels are fabricated in such a manner that the side walls and generally the bottom as well are joined by welded seams or spot welding. Precise joining occasions a certain amount of effort, and in addition, finishing work must often be performed at the welded locations.
Corner connecting rails are already known, which have two grooves extending at right angles to one another, into which flat sheets or panels can be inserted. However, frame-like cross struts or the like are required to secure the position of the connecting rails and of the sheets or panels relative to one another.